Jon Børre Ørbæk

The physical environment of Kongsfjorden–Krossfjorden, an Arctic fjord system in Svalbard

Kongsfjorden-Krossfjorden and the adjacent West Spitsbergen Shelf meet at the common mouth of the two fjord arms. This paper presents our most up-to-date information about the physical environment of this fjord system and identifies important gaps in knowledge. Particular attention is given to the steep physical gradients along the main fjord axis, as well as to seasonal environmental changes. Physical processes on different scales control the large-scale circulation and small-scale (irreversible) mixing of water and its constituents. It is shown that, in addition to the tide, run-off (glacier ablation, snowmelt, summer rainfall and ice calving) and local winds are the main driving forces acting on the upper water masses in the fjord system. The tide is dominated by the semi-diurnal component and the freshwater supply shows a marked seasonal variation pattern and also varies interannually. The wind conditions are characterized by prevailing katabatic winds, which at times are strengthened by the geostrophic wind field over Svalbard. Rotational dynamics have a considerable influence on the circulation patterns within the fjord system and give rise to a strong interaction between the fjord arms. Such dynamics are also the main reason why variations in the shelf water density field, caused by remote forces (tide and coastal winds), propagate as a Kelvin wave into the fjord system. This exchange affects mainly the intermediate and deep water, which is also affected by vertical convection processes driven by cooling of the surface and brine release during ice formation in the inner reaches of the fjord arms. Further aspects covered by this paper include the geological and geomorphological characteristics of the Kongsfjorden area, climate and meteorology, the influence of glaciers, freshwater supply, sea ice conditions, sedimentation processes as well as underwater radiation conditions. The fjord system is assumed to be vulnerable to possible climate changes, and thus is very suitable as a site for the demonstration and investigation of phenomena related to climate change.

Arctic Alpine ecosystems and people in a changing environment

Arctic-Alpine Ecosystems and People in a Changing Environment - Introduction.- Integrated aspects of environmental change: Climate change, UV radiation and long range transport of pollutants.- An environment at risk: Arctic indigenous peoples, local livelihoods and climate change.- Climate change and ecosystem response.- Climate variation in the European sector of the Arctic: Observations and scenarios.- Impact of climate change on arctic and alpine lakes: Effects on phenology and community dynamics.- Changes in growing season in Fennoscandia 1982-1999.- Northern climates and woody plant distribution.- Topographic complexity and terrestrial biotic response to high-latitude climate change: Variance is as important as the mean.- The flow of Atlantic water to the Nordic Seas and Arctic Ocean.- Climate variability and possible effects on arctic food chains: The role of Calanus.- Adjustment to reality: Social responses to climate changes in Greenland.- UV radiation and biological effects.- Factors, trends and scenarios of UV radiation in arctic-alpine environments.- Effects of enhanced UV-B radiation and epidermal UV screening in arctic and alpine plants.- Effects of UV radiation in arctic and alpine freshwater ecosystems.- Climate control of biological UV exposure in polar and alpine aquatic ecosystems.- Effects of UV radiation on seaweeds.- Climate and ozone change effects on UV-radiation and health risks.- Long range pollutants transport and ecological impacts.- Contaminants, global change and cold regions.- Modeling of long-range transport of contaminants from potential sources in the Arctic Ocean by water and sea ice.- Long-term atmospheric contaminant monitoring for the elucidation of airborne transport processes into polar regions.- Levels and effects of persistent organic pollutants in arctic animals.- Arctic health problems and environmental challenges in Greenland.

Physical and ecological processes in the marginal ice zone of the northern Barents Sea during the summer melt period

Abstract The main physical and ecological processes associated with the summer melt period in the marginal ice zone (MIZ) were investigated in a multidisciplinary research programme (ICE-BAR), which was carried out in the northern Barents Sea during June–August 1995–1996. This study provided simultaneous observations of a wide range of physical and chemical factors of importance for the melting processes of sea ice, from its southernmost margins at about 77.5°N to the consolidated Arctic pack ice at 81.5°N. This paper includes a description of the oceanographic processes, ice-density packing and structures in cores, optical properties of water masses and the ice, characteristics of the incident spectral radiation and chlorophyll — leading to primary production. Large seasonal and inter-annual variations in ice cover in the MIZ were evident from satellite images as well as ship observations. Even if the annual variation in ice extent may be large, the inter-annual variations may be even larger. The minimum observed ice extent in March, for example, can be smaller than the maximum observed ice extent in September. Oceanographic phenomena such as the semi-permanent lee polynyas found west and south-west of Kvitoya and Franz Josef Land and the bay of open water, the “Whalers Bay”, north of the Spitsbergen are structures which can change with time intervals of hours to decades. For example, the polynya south of Franz Josef Land was clearly evident in 1995 but was only seen for a short period in 1996. The observed variability in physical conditions directly affects the primary production in the MIZ. From early spring, solar radiation penetrates both leads and the ice itself, initiating algal production under the ice. Light measurements showed that the melt ponds act as windows, permitting the transmission of incoming solar radiation through to the underlying sea ice, thus, accelerating the melting process and enhancing the under-ice primary production. In June 1995, the N–S transect went through a pre-bloom area well inside the ice-covered part of the Barents Sea to a post-bloom phase in the open waters south of the ice edge. The biological conditions in the later season (August) of 1996 were considerably more variable. The longer N–S transect in August 1996 passed through areas with variable ice and oceanographic conditions, and different developmental stages of phytoplankton blooms were encountered. The previously adapted picture of a plankton bloom following the retreating ice edge northwards was not seen.

Spectral reflectance of melting snow in a high Arctic watershed on Svalbard: some implications for optical satellite remote sensing studies

Field campaigns were undertaken in May and June of 1992 and 1997 in order to study spectral reflectance characteristics of snow during melt-off. The investigations were performed on snow-covered tundra at Ny-Alesund, Svalbard (79°N). Spectral measurements were acquired with spectroradiometers covering wavelengths from 350 to 2500 nm. Supporting measurements such as snow thickness, density, content of liquid water, grain size and shape, stratification of snowpack, as well as cloud observations and air temperature, were monitored throughout the field campaigns. Spectral measurements demonstrate that the near-infrared albedo is most affected by the ongoing snow metamorphism while the albedo in the visible wavelength range is more strongly affected by surface pollution. Comparisons of spectral measurements and spectrally integrated measurements emphasize the need for narrow-band to broad-band conversion when applying satellite-derived albedo to surface energy-balance calculations. As an example, Landsat TM Band 4 albedo is shown to produce slightly high albedo values compared to the spectrally integrated albedo (285–2800 nm). Daily albedo measurements from 1981–1997 show that the albedo normally drops from 80% to bare ground levels (∽10%) within two to four weeks and the date when the tundra becomes snow-free varies from early June to early July. Thus, the changing spectral characteristics of snow during melt-off combined with a general rapid decrease in albedo call for cautious use of satellite-derived albedo, especially when used as absolute numbers. Our data also illustrate the effect of cloud cover on surface albedo for an event in which the integrated albedo increased by 7% under cloudy conditions compared to clear skies without changes of surface properties. Finally, the reflectance of snow increases relative to nadir for measurements facing the sun and at azimuths 90° and 180° by 8, 15, 19, and 26% for viewing angles 15°, 30°, 45°, and 60°, respectively, due to anisotropic reflection. Copyright

Attenuation of solar radiation in Arctic snow: field observations and modelling

Abstract Solar radiation was measured above and in the snowpack on Svalbard using a spectroradiometer and a quantum meter measuring average photosynthetically active radiation (PAR). In order to specify the effect of melting on the snow’s radiation properties, all measurements were performed before and during the melt season in May and June 1997 and 1998. Along with the radiation measurements, physical and structural snow properties were logged in snow pits. A physically based model was used to simulate the penetration of radiation into the snow The model formulation accounts for the spectrally dependent interactions between the radiation and snow grains, and requires inputs of the incoming solar radiation spectrum and the vertical snow density and grain-size. The vertical radiation-flux profile was computed using a two-stream radiation approximation where the absorption and reflection coefficients are related to the surface albedo, solar spectrum, grain-size and number of grains per unit volume. In general, snow before the onset of melt attenuates solar radiation more than coarser-grained snow that has been exposed to melting conditions. Quantum-meter measurements of PAR before and during melt can be explained by model outputs using both constant and variable extinction coefficients. Spectroradiometer measurements at fixed depth levels showed, in addition, that impurities in the snow reduce its transparency and therefore have the opposite effect to aging.

Radiometric investigation of different snow covers in Svalbard

This paper examines the relationship between reflectance and physical characteristics of the snow cover in the Arctic. Field data were acquired for different snow and ice surfaces during a survey carried out at Ny-Ålesund, Svalbard, in spring 1998. In each measurement reflectance in the spectral range 350 - 2500 nm, snow data (including temperature, grain size and shape, density and water content), surface layer morphology, and vertical profile of the snow pack were recorded detailed analysis of reflectance based on the physical was performed. Field reflectance data were also re-sampled at the spectral intervals of Landsat TM to compare the ability of identifying different snow targets at discrete wavelength intervals. This analysis shows that reliable data on snow structure and thickness are necessary to understand albedo changes of the snow surfaces.

Integrated aspects of environmental change: Climate change, UV radiation and long range transport of pollutants

Obviously, the many challenges involving climate and stratospheric change, pollutant transport and social changes are related. A number of other significant dependencies also naturally exist between the various aspects of environmental change parameters and human activities in arctic and alpine areas. The scope here is not to give a complete review of all single processes but to outline the level of interaction between the main contemporary challenges in environmental change, on the basis of the studies presented in the book. Both with respect to the physical processes as well as dealing with their biological impacts and the anthropogenic forcing factors, the changes related to the climate change processes, long range transported pollutants and UV radiation, can not be treated alone or independently but need to be analysed as multiple pressures of the high latitude and high altitude, arctic and alpine environments.